Lie Detector Based on Monitoring of Pupil Dilation

ABSTRACT

Deception can be evaluated by presenting a set of sentences or words to a testee, including some sentences or words that are expected to evoke significant pupil dilation in a testee who is lying and other sentences or words that are not expected to evoke significant pupil dilation in the testee. Changes in the testee&#39;s pupil size are compared to ascertain whether a pupil-dilation response to certain sentences or words is larger than for other sentences or words, and an indication of deceptiveness or non-deceptiveness is output based on the results of the ascertaining.

BACKGROUND

Polygraphs, popularly referred to as lie detectors, measurephysiological indicators of stress, which is an indicator of lying. Whena person lies, they experience typical autonomic reactions, triggered bystress, that are not easily controlled by the conscious mind. Theseautonomic reactions may include an increase in skin conductivity, heartrate, respiration rate, blood pressure, capillary dilation, and muscularmovement. The polygraph detects these autonomic reactions. It turns out,however, that these same autonomic reactions can result from otherfactors associated with and emotional states such as: fear, anger,familiarity, significance to the subject, and surprise. This decreasesthe capability of a polygraph to detect liars with high sensitivity andspecificity. In addition, some people have found ways to cheat apolygraph system. Examples include taking sedatives to reduce anxiety,using an antiperspirant to prevent sweating, and positioning pins orbiting parts of the mouth after each question to present a constantphysiological response. Moreover, polygraphs are intrusive, require anexpert examiner, can be fooled, and cannot be used for screening crowdsor for working in the field because a single polygraph examination cantake hours.

SUMMARY OF THE INVENTION

One aspect of the invention is directed to a first apparatus forevaluating whether a testee is being deceptive. The first apparatuscomprises an image sensor configured to capture a plurality ofsequential images of the testee's pupil; a processor configured todetermine a size of the testee's pupil in the plurality of sequentialimages; a circuit that generates an audio output; and a controller. Thecontroller is programmed to control the circuit so that the circuitoutputs an audio signal corresponding to a set of sentences. The set ofsentences includes an initial sentence, a first-type sentence, and aplurality of second-type sentences. The first-type sentence is expectedto evoke significant pupil dilation in a testee who is being deceptiveand not to evoke significant pupil dilation in a testee who is not beingdeceptive, and each of the second-type sentences is not expected toevoke significant pupil dilation in the testee. The initial sentence isoutput prior to the outputting of the first-type sentence and theplurality of second-type sentences. The controller is further programmedto monitor changes in the determined size of the testee's pupil duringthe outputting of the first-type sentence and the plurality ofsecond-type sentences and during any responses to the first-typesentence and the plurality of second-type sentences made by the testee.The controller is further programmed to compare changes in thedetermined size of the testee's pupil in response to the first-typesentence with changes in the determined size of the testee's pupil inresponse to the second-type sentences to ascertain whether apupil-dilation response to the first-type sentence is larger than apupil-dilation response to each of the plurality of second-typesentences. The controller is further programmed to output an indicationof deceptiveness or non-deceptiveness based on the ascertaining ofwhether the pupil-dilation response to the first-type sentence is largerthan the pupil-dilation response to each of the plurality of second-typesentences. The first-type sentence and each of the second-type sentencesare all in the same language. The average volume of each of the portionsof the audio signal that corresponds to a second-type sentence is within10 dB of the average volume of the portion of the audio signal thatcorresponds to the first-type sentence. The first-type sentence and eachof the second-type sentences has a duration of less than 5 s. And gapsof at least 3 s are interposed between adjacent sentences within the setof sentences.

In some embodiments of the first apparatus, the controller is furtherprogrammed to (a) output an indication of deceptiveness when thecontroller ascertains that the pupil-dilation response to the first-typesentence is larger than the pupil-dilation response to each of theplurality of second-type sentences, and (b) output an indication ofnon-deceptiveness when the controller ascertains that the pupil-dilationresponse to the first-type sentence is not larger than thepupil-dilation response to each of the plurality of second-typesentences.

In some embodiments of the first apparatus, portions of the audio signalcorresponding to the first-type sentence and the plurality ofsecond-type sentences are output using the same voice, the entire set ofsentences is output within 2 minutes, and the set of sentences that isoutput contains between 4 and 10 sentences.

In some embodiments of the first apparatus, the controller is furtherprogrammed to ascertain whether a pupil-dilation response to thefirst-type sentence is at least 10% larger than a pupil-dilationresponse to each of the plurality of second-type sentences.

Some embodiments of the first apparatus further comprise an audioamplifier and a speaker. In these embodiments, the audio amplifierreceives the audio output from the circuit, and an output of the audioamplifier drives the speaker.

Some embodiments of the first apparatus further comprise a light sourceconfigured to control a level of illumination that arrives at thetestee's pupil in response to instructions received from the controller.In these embodiments, the controller is further programmed to send theinstructions to the light source.

In some embodiments of the first apparatus, a single integrated circuitserves as both the processor and the controller.

In some embodiments of the first apparatus, the set of sentences furtherincludes a third-type sentence that is expected to evoke significantpupil dilation in a testee who is not being deceptive. In theseembodiments the controller is further programmed to (a) compare changesin the testee's pupil size in response to the third-type sentence withchanges in the testee's pupil size in response to the first-typesentence to ascertain whether a pupil-dilation response to thefirst-type sentence is larger than a pupil-dilation response to thethird-type sentence, (b) output an indication of deceptiveness when thecontroller ascertains that the pupil-dilation response to the first-typesentence is larger than the pupil-dilation response to each of theplurality of second-type sentences and is also larger than thepupil-dilation response to the third-type sentence, and (c) output anindication of non-deceptiveness when the controller ascertains that thepupil-dilation response to the third-type sentence is larger than thepupil-dilation response to the first-type sentence or when thecontroller ascertains that the pupil-dilation response to the first-typesentence is not larger than the pupil-dilation response to each of theplurality of second-type sentences.

In some embodiments of the first apparatus, the grammatical structure,duration, level of complexity, and language style of each of thesecond-type sentences is similar to the grammatical structure, duration,level of complexity, and language style of the first-type sentence.

In some embodiments of the first apparatus, the first-type sentenceincludes a material keyword, each of the second-type sentences includesa respective other keyword, and the position of the respective otherkeyword within each of the second-type sentences is similar to theposition of the material keyword within the first-type sentence. Any twogiven keywords are deemed to have a similar position within a respectivesentence when the two given keywords are either (a) both positioned inthe initial one-third of the respective sentence, (b) both positioned inthe middle one-third of the respective sentence, or (c) both positionedin the last one-third of the respective sentence.

Another aspect of the invention is directed to a first method ofevaluating whether a testee is being deceptive. The first methodcomprises presenting a set of sentences to the testee. The set ofsentences includes an initial sentence, a first-type sentence, and aplurality of second-type sentences. The first-type sentence is expectedto evoke significant pupil dilation in a testee who is being deceptiveand not to evoke significant pupil dilation in a testee who is not beingdeceptive. Each of the second-type sentences is not expected to evokesignificant pupil dilation in the testee. The initial sentence ispresented to the testee prior to the presenting of the first-typesentence and the plurality of second-type sentences. The first methodalso comprises monitoring changes in the testee's pupil size during thepresenting of the first-type sentence and the plurality of second-typesentences and during any responses to the first-type sentence and theplurality of second-type sentences made by the testee. The first methodalso comprises comparing changes in the testee's pupil size in responseto the first-type sentence with changes in the testee's pupil size inresponse to the second-type sentences to ascertain whether apupil-dilation response to the first-type sentence is larger than apupil-dilation response to each of the plurality of second-typesentences. And the first method also comprises outputting an indicationof deceptiveness or non-deceptiveness based on the ascertaining ofwhether the pupil-dilation response to the first-type sentence is largerthan the pupil-dilation response to each of the plurality of second-typesentences. In this first method, the first-type sentence and each of thesecond-type sentences are all in the same language, the average volumeof each of the second-type sentences is within 10 dB of the averagevolume of the first-type sentence, the first-type sentence and each ofthe second-type sentences has a duration of less than 5 s, and gaps ofat least 3 s are interposed between adjacent sentences within the set ofsentences.

In some instances of the first method, the outputting comprises (a)outputting an indication of deceptiveness when the comparing revealsthat the pupil-dilation response to the first-type sentence is largerthan the pupil-dilation response to each of the plurality of second-typesentences, and (b) outputting an indication of non-deceptiveness whenthe comparing reveals that the pupil-dilation response to the first-typesentence is not larger than the pupil-dilation response to each of theplurality of second-type sentences.

In some instances of the first method, the first-type sentence and theplurality of second-type sentences are all in the same voice, the entireset of sentences is presented to the testee within 2 minutes, and theset of sentences that is presented to the testee contains between 4 and10 sentences.

Some instances of the first method further comprise controlling a levelof illumination that arrives at the testee's pupil.

In some instances of the first method, the set of sentences furtherincludes a third-type sentence that is expected to evoke significantpupil dilation in a testee who is not being deceptive. In theseinstances, the method further comprises (a) comparing changes in thetestee's pupil size in response to the third-type sentence with changesin the testee's pupil size in response to the first-type sentence toascertain whether a pupil-dilation response to the first-type sentenceis larger than a pupil-dilation response to the third-type sentence, (b)outputting an indication of deceptiveness when a pupil-dilation responseto the first-type sentence is larger than the pupil-dilation response toeach of the plurality of second-type sentences and is also larger thanthe pupil-dilation response to the third-type sentence, and (c)outputting an indication of non-deceptiveness when the pupil-dilationresponse to the third-type sentence is larger than the pupil-dilationresponse to the first-type sentence or when the pupil-dilation responseto the first-type sentence is not larger than the pupil-dilationresponse to each of the plurality of second-type sentences.

In some instances of the first method, the grammatical structure,duration, level of complexity, and language style of each of thesecond-type sentences is similar to the grammatical structure, duration,level of complexity, and language style of the first-type sentence.

In some instances of the first method, the first-type sentence includesa material keyword, and each of the second-type sentences includes arespective other keyword. The position of the respective other keywordwithin each of the second-type sentences is similar to the position ofthe material keyword within the first-type sentence. Any two givenkeywords are deemed to have a similar position within a respectivesentence when the two given keywords are either (a) both positioned inthe initial one-third of the respective sentence, (b) both positioned inthe middle one-third of the respective sentence, or (c) both positionedin the last one-third of the respective sentence.

Another aspect of the invention is directed to a second apparatus forevaluating whether a testee is being deceptive. The second apparatuscomprises an image sensor configured to capture a plurality ofsequential images of the testee's pupil; a processor configured todetermine a size of the testee's pupil in the plurality of sequentialimages; a circuit that generates an audio output; and a controller. Thecontroller is programmed to control the circuit so that the circuitoutputs an audio signal corresponding to (a) an introductory phrase orsentence and (b) a set of words. The set of words is output after theintroductory phrase or sentence, with gaps of at least 2 s interposedbetween words within the set. The set of words includes an initial word,a first-type word, and a plurality of second-type words. The first-typeword is expected to evoke significant pupil dilation in a testee who isbeing deceptive and not to evoke significant pupil dilation in a testeewho is not being deceptive. Each of the second-type words is notexpected to evoke significant pupil dilation in the testee. The initialword is presented to the testee prior to the presenting of thefirst-type word and the plurality of second-type words. The entire setof words is presented to the testee in less than 2 minutes, and the setof words contains less than 20 words. The controller is furtherprogrammed to monitor changes in the testee's pupil size during thepresenting of the first-type word and the plurality of second-type wordsand during any responses to the first-type word and the plurality ofsecond-type words made by the testee. The controller is furtherprogrammed to compare changes in the testee's pupil size in response tothe first-type word with changes in the testee's pupil size in responseto the second-type words to ascertain whether a pupil-dilation responseto the first-type word is larger than a pupil-dilation response to eachof the plurality of second-type words. And the controller is furtherprogrammed to output an indication of deceptiveness or non-deceptivenessbased on the ascertaining of whether the pupil-dilation response to thefirst-type word is larger than the pupil-dilation response to each ofthe plurality of second-type words. In these embodiments, the first-typeword and each of the second-type words are all in the same language, andthe first-type word and each of the second-type words all have volumeswithin 10 dB of each other.

In some embodiments of the second apparatus, the controller is furtherprogrammed to (a) output an indication of deceptiveness when thecontroller ascertains that the pupil-dilation response to the first-typeword is larger than the pupil-dilation response to each of the pluralityof second-type words, and (b) output an indication of non-deceptivenesswhen the controller ascertains that the pupil-dilation response to thefirst-type word is not larger than the pupil-dilation response to eachof the plurality of second-type words.

In some embodiments of the second apparatus, the controller is furtherprogrammed to control a level of illumination that arrives at thetestee's pupil.

In some embodiments of the second apparatus, the set of words furtherincludes a third-type word that is expected to evoke significant pupildilation in a testee who is not being deceptive. In these embodiments,the controller is further programmed to (a) compare changes in thetestee's pupil size in response to the third-type word with changes inthe testee's pupil size in response to the first-type word to ascertainwhether a pupil-dilation response to the first-type word is larger thana pupil-dilation response to the third-type word, (b) output anindication of deceptiveness when the controller ascertains that thepupil-dilation response to the first-type word is larger than thepupil-dilation response to each of the plurality of second-type wordsand is also larger than the pupil-dilation response to the third-typeword, and (c) output an indication of non-deceptiveness when thecontroller ascertains that the pupil-dilation response to the third-typeword is larger than the pupil-dilation response to the first-type wordor when the controller ascertains that the pupil-dilation response tothe first-type word is not larger than the pupil-dilation response toeach of the plurality of second-type words.

In some embodiments of the second apparatus, the first-type word andeach of the second-type words are presented in the same voice.Optionally, in these embodiments, the first-type word and each of thesecond-type words have a similar level of complexity and a similarlanguage style.

Another aspect of the invention is directed to a second method ofevaluating whether a testee is being deceptive. The second methodcomprises presenting an introductory phrase or sentence to the testee.The second method also comprises presenting a set of words to the testeeafter the introductory phrase or sentence has been presented to thetestee, with gaps of at least 2 s interposed between words within theset. The set of words includes an initial word, a first-type word, and aplurality of second-type words. The first-type word is expected to evokesignificant pupil dilation in a testee who is being deceptive and not toevoke significant pupil dilation in a testee who is not being deceptive.Each of the second-type words is not expected to evoke significant pupildilation in the testee. The initial word is presented to the testeeprior to the presenting of the first-type word and the plurality ofsecond-type words, the entire set of words is presented to the testee inless than 2 minutes, and the set of words contains less than 20 words.The second method also comprises monitoring changes in the testee'spupil size during the presenting of the first-type word and theplurality of second-type words and during any responses to thefirst-type word and the plurality of second-type words made by thetestee. The second method also comprises comparing changes in thetestee's pupil size in response to the first-type word with changes inthe testee's pupil size in response to the second-type words toascertain whether a pupil-dilation response to the first-type word islarger than a pupil-dilation response to each of the plurality ofsecond-type words. The second method also comprises outputting anindication of deceptiveness or non-deceptiveness based on theascertaining of whether the pupil-dilation response to the first-typeword is larger than the pupil-dilation response to each of the pluralityof second-type words. In the second method, the first-type word and eachof the second-type words are all in the same language, and thefirst-type word and each of the second-type words all have volumeswithin 10 dB of each other.

In some instances of the second method, the outputting comprises (a)outputting an indication of deceptiveness when the comparing revealsthat the pupil-dilation response to the first-type word is larger thanthe pupil-dilation response to each of the plurality of second-typewords, and (b) outputting an indication of non-deceptiveness when thecomparing reveals that the pupil-dilation response to the first-typeword is not larger than the pupil-dilation response to each of theplurality of second-type words.

Some instances of the second method further comprise controlling a levelof illumination that arrives at the testee's pupil.

In some instances of the second method, the set of words furtherincludes a third-type word that is expected to evoke significant pupildilation in a testee who is not being deceptive. In these instances, thesecond method further comprises (a) comparing changes in the testee'spupil size in response to the third-type word with changes in thetestee's pupil size in response to the first-type word to ascertainwhether a pupil-dilation response to the first-type word is larger thana pupil-dilation response to the third-type word, (b) outputting anindication of deceptiveness when the pupil-dilation response to thefirst-type word is larger than the pupil-dilation response to each ofthe plurality of second-type words and is also larger than thepupil-dilation response to the third-type word, and (c) outputting anindication of non-deceptiveness when the pupil-dilation response to thethird-type word is larger than the pupil-dilation response to thefirst-type word or when the pupil-dilation response to the first-typeword is not larger than the pupil-dilation response to each of theplurality of second-type words.

In some instances of the second method, the first-type word and each ofthe second-type words are presented in the same voice. Optionally, inthese instances, the first-type word and each of the second-type wordshave a similar level of complexity and a similar language style.

Another aspect of the invention is directed to a third apparatus forevaluating whether a testee is being deceptive. The third apparatuscomprises an image sensor configured to capture a plurality ofsequential images of the testee's pupil; a processor configured todetermine a size of the testee's pupil in the plurality of sequentialimages; a circuit that generates an audio output; and a controller. Thecontroller is programmed to control the circuit so that the circuitoutputs an audio signal corresponding to a set of sentences. The set ofsentences includes an initial sentence and at least three first-typesentences. Each of the first-type sentences is expected to evokesignificant pupil dilation in a testee who is being deceptive and not toevoke significant pupil dilation in a testee who is not being deceptive.The initial sentence is output prior to the outputting of the first-typesentences. The controller is further programmed to monitor changes inthe determined size of the testee's pupil during the outputting of thefirst-type sentences and during any responses to the first-typesentences made by the testee. The controller is further programmed tocompare changes in the determined size of the testee's pupil in responseto each of the first-type sentences to ascertain whether apupil-dilation response to each respective one of the first-typesentences is at least 10% larger than a pupil-dilation response to atleast two of the other first-type sentences. And the controller isfurther programmed to output an indication of deceptiveness ornon-deceptiveness for at least one of the first-type sentences based ona result of the ascertaining. In the third apparatus, the first-typesentences are all in the same language, the average volume of each ofthe portions of the audio signal that corresponds to each of thefirst-type sentences are all within 10 dB of each other, each of thefirst-type sentences has a duration of less than 5 s, and gaps of atleast 3 s are interposed between adjacent sentences within the set ofsentences.

In some embodiments of the third apparatus, the controller is furtherprogrammed to (a) output an indication of deceptiveness for a respectiveone of the first-type sentences when the controller ascertains that thepupil-dilation response to the respective first-type sentence is atleast 10% larger than a pupil-dilation response to at least two of theother first-type sentences, and (b) output an indication ofnon-deceptiveness when the controller ascertains that no pupil-dilationresponse to any given one of the first-type sentences is at least 10%larger than a pupil-dilation response to at least two of the otherfirst-type sentences.

In some embodiments of the third apparatus, portions of the audio signalcorresponding to the first-type sentences are output using the samevoice, the entire set of sentences is output within 2 minutes, and theset of sentences that is output contains between 4 and 10 sentences.

In some embodiments of the third apparatus, the controller is furtherprogrammed to ascertain whether a pupil-dilation response to any givenone of the first-type sentences is at least 20% larger than apupil-dilation response to at least two of the other first-typesentences.

Some embodiments of the third apparatus further comprise an audioamplifier and a speaker. The audio amplifier receives the audio outputfrom the circuit, and an output of the audio amplifier drives thespeaker.

Some embodiments of the third apparatus further comprise a light sourceconfigured to control a level of illumination that arrives at thetestee's pupil in response to instructions received from the controller.In these embodiments, the controller is further programmed to send theinstructions to the light source.

In some embodiments of the third apparatus, a single integrated circuitserves as both the processor and the controller.

In some embodiments of the third apparatus, the set of sentences furtherincludes a third-type sentence that is expected to evoke significantpupil dilation in a testee who is not being deceptive. In theseembodiments, the controller is further programmed to (a) compare changesin the testee's pupil size in response to the third-type sentence withchanges in the testee's pupil size in response to each of the first-typesentences, (b) output an indication of deceptiveness for a respectiveone of the first-type sentences when the controller ascertains that thepupil-dilation response to the respective first-type sentence is atleast 10% larger than the pupil-dilation response to at least two of theother first-type sentences and is also larger than the pupil-dilationresponse to the third-type sentence, and (c) output an indication ofnon-deceptiveness when the controller ascertains that the pupil-dilationresponse to each of the first-type sentences is smaller than thepupil-dilation response to the third-type sentence or when thecontroller ascertains that the pupil-dilation response to none of thefirst-type sentences is at least 10% larger than the pupil-dilationresponse to at least two other first-type sentences.

In some embodiments of the third apparatus, the grammatical structure,duration, level of complexity, and language style of all the first-typesentences are similar.

In some embodiments of the third apparatus, each of the first-typesentences includes a respective keyword, and the position of therespective keyword within each of the first-type sentences is similar.Any two given keywords are deemed to have a similar position within arespective sentence when the two given keywords are either (a) bothpositioned in the initial one-third of the respective sentence, (b) bothpositioned in the middle one-third of the respective sentence, or (c)both positioned in the last one-third of the respective sentence.

Another aspect of the invention is directed to a third method ofevaluating whether a testee is being deceptive. The third methodcomprises presenting a set of sentences to the testee. The set ofsentences includes an initial sentence and at least three first-typesentences. Each of the first-type sentences is expected to evokesignificant pupil dilation in a testee who is being deceptive and not toevoke significant pupil dilation in a testee who is not being deceptive.The initial sentence is presented to the testee prior to the presentingof the first-type sentences. The third method also comprises monitoringchanges in the testee's pupil size during the presenting of thefirst-type sentences and during any responses to the first-typesentences made by the testee. The third method also comprises comparingchanges in the testee's pupil size in response to each of the first-typesentences to ascertain whether a pupil-dilation response to eachrespective one of the first-type sentences is at least 10% larger than apupil-dilation response to at least two of the other first-typesentences. The third method also comprises outputting an indication ofdeceptiveness or non-deceptiveness for at least one of the first-typesentences based on a result of the ascertaining. The first-typesentences are all in the same language, the average volume of each ofthe first-type sentences is within 10 dB of each other, each of thefirst-type sentences has a duration of less than 5 s, and gaps of atleast 3 s are interposed between adjacent sentences within the set ofsentences.

In some instances of the third method, the outputting comprises (a)outputting an indication of deceptiveness for a respective one of thefirst-type sentences when the comparing reveals that the pupil-dilationresponse to the respective first-type sentence is at least 10% largerthan a pupil-dilation response to at least two of the other first-typesentences, and (b) outputting an indication of non-deceptiveness whenthe comparing reveals that no pupil-dilation response to any given oneof the first-type sentences is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type sentences.

In some instances of the third method, the first-type sentences are allin the same voice, the entire set of sentences is presented to thetestee within 2 minutes, and the set of sentences that is presented tothe testee contains between 4 and 10 sentences.

Some instances of the third method further comprise controlling a levelof illumination that arrives at the testee's pupil.

In some instances of the third method, the set of sentences furtherincludes a third-type sentence that is expected to evoke significantpupil dilation in a testee who is not being deceptive. In theseinstances, the third method further comprises (a) comparing changes inthe testee's pupil size in response to the third-type sentence withchanges in the testee's pupil size in response to each of the first-typesentences, (b) outputting an indication of deceptiveness for arespective one of the first-type sentences when a pupil-dilationresponse to the respective first-type sentences is at least 10% largerthan the pupil-dilation response to at least two of the other first-type sentences and is also larger than the pupil-dilation response tothe third-type sentence, and (c) outputting an indication ofnon-deceptiveness when the pupil-dilation response to each of thefirst-type sentences is smaller than the pupil-dilation response to thethird-type sentence or when the pupil-dilation response to none of thefirst-type sentences is at least 10% larger than the pupil-dilationresponse to at least two other first-type sentences.

In some instances of the third method, the grammatical structure,duration, level of complexity, and language style of all the first-typesentences are similar.

In some instances of the third method, each of the first-type sentencesincludes a respective keyword, and the position of the respectivekeyword within each of the first-type sentences is similar. Any twogiven keywords are deemed to have a similar position within a respectivesentence when the two given keywords are either (a) both positioned inthe initial one-third of the respective sentence, (b) both positioned inthe middle one-third of the respective sentence, or (c) both positionedin the last one-third of the respective sentence.

Another aspect of the invention is directed to a fourth apparatus forevaluating whether a testee is being deceptive. The fourth apparatuscomprises an image sensor configured to capture a plurality ofsequential images of the testee's pupil; a processor configured todetermine a size of the testee's pupil in the plurality of sequentialimages; a circuit that generates an audio output; and a controller. Thecontroller is programmed to control the circuit so that the circuitoutputs an audio signal corresponding to (a) an introductory phrase orsentence and (b) a set of words. The set of words is output after theintroductory phrase or sentence, with gaps of at least 2 s interposedbetween words within the set. The set of words includes an initial wordand at least three first-type words. Each of the first-type words isexpected to evoke significant pupil dilation in a testee who is beingdeceptive and not to evoke significant pupil dilation in a testee who isnot being deceptive. The initial word is presented to the testee priorto the presenting of the first-type words, the entire set of words ispresented to the testee in less than 2 minutes, and the set of wordscontains less than 20 words. The controller is further programmed tomonitor changes in the testee's pupil size during the presenting of thefirst-type words and during any responses to the first-type words madeby the testee. The controller is further programmed to compare changesin the testee's pupil size in response to each of the first-type wordsto ascertain whether a pupil-dilation response to each respective one ofthe first-type words is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type words. And thecontroller is further programmed to output an indication ofdeceptiveness or non-deceptiveness for at least one of the first-typewords based on a result of the ascertaining. The first-type words areall in the same language, and the first-type words all have volumeswithin 10 dB of each other.

In some embodiments of the fourth apparatus, the controller is furtherprogrammed to (a) output an indication of deceptiveness for a respectiveone of the first-type words when the controller ascertains that thepupil-dilation response to the respective first-type word is at least10% larger than a pupil-dilation response to at least two of the otherfirst-type words, and (b) output an indication of non-deceptiveness whenthe controller ascertains that no pupil-dilation response to any givenone of the first-type words is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type words.

In some embodiments of the fourth apparatus, the controller is furtherprogrammed to control a level of illumination that arrives at thetestee's pupil.

In some embodiments of the fourth apparatus, the set of words furtherincludes a third-type word that is expected to evoke significant pupildilation in a testee who is not being deceptive. In these embodiments,the controller is further programmed to (a) compare changes in thetestee's pupil size in response to the third-type word with changes inthe testee's pupil size in response to each of the first-type words, (b)output an indication of deceptiveness for a respective one of thefirst-type words when the controller ascertains that the pupil-dilationresponse to the respective first-type word is at least 10% larger thanthe pupil-dilation response to at least two of the other first-typewords and is also larger than the pupil-dilation response to thethird-type word, and (c) output an indication of non-deceptiveness whenthe controller ascertains that the pupil-dilation response to each ofthe first-type words is smaller than the pupil-dilation response to thethird-type word or when the controller ascertains that thepupil-dilation response to none of the first-type words is at least 10%larger than the pupil-dilation response to at least two other first-typewords.

In some embodiments of the fourth apparatus, all the first-type wordsare presented in the same voice. Optionally, in these embodiments, allthe first-type words have a similar level of complexity and a similarlanguage style.

Another aspect of the invention is directed to a fourth method ofevaluating whether a testee is being deceptive. The fourth methodcomprises presenting an introductory phrase or sentence to the testee.The fourth method also comprises presenting a set of words to the testeeafter the introductory phrase or sentence has been presented to thetestee, with gaps of at least 2 s interposed between words within theset. The set of words includes an initial word and at least threefirst-type words. Each of the first-type words is expected to evokesignificant pupil dilation in a testee who is being deceptive and not toevoke significant pupil dilation in a testee who is not being deceptive.The initial word is presented to the testee prior to the presenting ofthe first-type words, the entire set of words is presented to the testeein less than 2 minutes, and the set of words contains less than 20words. The fourth method also comprises monitoring changes in thetestee's pupil size during the presenting of the first-type words andduring any responses to the first-type words made by the testee. Thefourth method also comprises comparing changes in the testee's pupilsize in response to each of the first-type words to ascertain whether apupil-dilation response to each respective one of the first-type wordsis at least 10% larger than a pupil-dilation response to at least two ofthe other first-type words. The fourth method also comprises outputtingan indication of deceptiveness or non-deceptiveness for at least one ofthe first-type words based on a result of the ascertaining. Thefirst-type words are all in the same language, and the first-type wordsall have volumes within 10 dB of each other.

In some instances of the fourth method, the outputting comprises (a)outputting an indication of deceptiveness for a respective one of thefirst-type words when the comparing reveals that the pupil-dilationresponse to the respective first-type word is at least 10% larger than apupil-dilation response to at least two of the other first-type words,and (b) outputting an indication of non-deceptiveness when the comparingreveals that no pupil-dilation response to any given one of thefirst-type words is at least 10% larger than a pupil-dilation responseto at least two of the other first-type words.

Some instances of the fourth method further comprise controlling a levelof illumination that arrives at the testee's pupil.

In some instances of the fourth method, the set of words furtherincludes a third-type word that is expected to evoke significant pupildilation in a testee who is not being deceptive. In these instances, themethod further comprises (a) comparing changes in the testee's pupilsize in response to the third-type word with changes in the testee'spupil size in response to each of the first-type words, (b) outputtingan indication of deceptiveness for a respective one of the first-typewords when the pupil-dilation response to the respective first-type wordis at least 10% larger than the pupil-dilation response to at least twoof the other first-type words and is also larger than the pupil-dilationresponse to the third-type word, and (c) outputting an indication ofnon-deceptiveness when the pupil-dilation response to each of thefirst-type words is smaller than the pupil-dilation response to thethird-type word or when the pupil-dilation response to none of thefirst-type words is at least 10% larger than the pupil-dilation responseto at least two other first-type words.

In some instances of the fourth method, all the first-type words arepresented in the same voice. Optionally, in these instances, all thefirst-type words have a similar level of complexity and a similarlanguage style.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for evaluating whether a testee isbeing deceptive.

FIG. 2 is a flowchart for presenting a set of sentences to a testee, andevaluating deceptiveness by monitoring changes in size of the testee'spupil.

FIG. 3 depicts an exemplary time sequence for presenting the set ofsentences to the testee.

FIG. 4 depicts an example of presenting a set of sentences to a testee,where each of the sentences includes a respective keyword.

FIG. 5 depicts an example of changes in pupil size over time for atruthful testee and for a testee who is being deceptive.

FIG. 6 depicts an exemplary time sequence for presenting a different setof sentences to the testee.

FIG. 7 depicts another example of changes in pupil size over time for atruthful testee and for a testee who is being deceptive.

FIG. 8 is a flowchart for presenting an other set of sentences to atestee, and evaluating deceptiveness by monitoring changes in the sizeof the testee's pupil.

FIG. 9 depicts an example of a time sequence for presenting the set ofwords to the testee in the FIG. 8 embodiment.

FIG. 10 is a flowchart for presenting a set of words to a testee, andevaluating deceptiveness by monitoring changes in size of the testee'spupil.

FIG. 11 depicts an example of a time sequence for presenting the set ofwords to the testee in the FIG. 10 embodiment.

Various embodiments are described in detail below with reference to theaccompanying drawings, wherein like reference numerals represent likeelements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram of a system for evaluating whether a testee isbeing deceptive (e.g., whether the testee is lying or telling thetruth). Operation of the system is controlled by a processor/controller20. The processor/controller 20 performs both image processingoperations and control operations, both of which are described below.The processor/controller 20 has access to a sufficient amount of RAM/SSD21 (e.g., 16 GB of RAM and 512 GB of solid state disk space). In someembodiments, the processor/controller 20 is implemented using a singleintegrated circuit (e.g., an Intel Core i7 processor). But inalternative embodiments, the processor and control functions may bedivided among two or more integrated circuits.

The system outputs audio signals to the testee via an audio circuit 30(which optionally includes an audio frequency amplifier) that drives aspeaker 32 or an alternative transducer (e.g. headphones), and the audiosignals that the testee hears will depend on the signals that theprocessor/controller 20 sends to the audio circuit 30. As describedbelow, the audio signals that are provided to the testee may be in theform of a set of sentences (e.g. questions, statements) or set of words.The processor/controller 20 is programmed to control the audio circuit30 so that the audio circuit 30 outputs an audio signal corresponding tothe set of sentences or the set of words. In some embodiments, this maybe accomplished by pre-recording the set of sentences or the set ofwords and subsequently outputting the prerecorded sentences or words. Inother embodiments, this may be accomplished by executing appropriatetext-to-speech code.

A person's pupil-dilation responses may depend on a variety of factorsincluding but not limited to the person's cognitive state, cognitiveload, neuropsychological status, neurophysiological status, eye anatomy,illness, injury, intoxication, current state of mind, emotions (e.g.,stress, fatigue, excitement, fear, surprise, anger,familiarity/affection) and personal characteristics. The embodimentsdescribed herein operate by evoking pupil-dilation responses from thetestee (the source of the testee's pupil-dilation responses may be, forexample, cognitive and/or emotional), analyzing those pupil-dilationresponses, and deciding if the testee is being deceptive based on theanalysis.

The system evaluates whether a testee is being deceptive by monitoringchanges in the size of the testee's pupil. This is accomplished using animage sensor that captures a sequence of image frames that include thetestee's pupil. The image sensor may be implemented, for example, usinga camera 25 with a lens 26 that is aimed at the testee's face. In somepreferred embodiments, the camera 25 is a UI-3060CP from IDS ImagingDevelopment Systems GmbH, and the lens 26 is an M3514-MP 35 mm lens fromComputar. Optionally, a filter 27 may be positioned in front of the lens26. In some preferred embodiments, the filter 27 is an LP830-25.4 fromMidopt. In some embodiments, frame rates between 30 frames per second(fps) and 120 fps are used to capture the images that include thetestee's pupil. The number of image frames that must be captured willdepend on the frame rate. For example, when the frame rate is 30 fps,and image data is captured for one minute, 1800 image frames will becaptured by the image sensor and forwarded to the processor/controller20.

The image data captured by the image sensor is provided to theprocessor/controller 20. The processor/controller 20 executes imageprocessing routines to locate the testee's pupil in each frame of imagedata. One example of a suitable approach that may be used to locate thetestee's pupil is to analyze each image using a threshold to binarizethe image, apply a connected component algorithm to find all objects inthe image, and detect the pupil by selecting the object which is roundand has the correct physical size. A variety of alternative approacheswill be apparent to persons skilled in the relevant art. After locatingthe testee's pupil in each frame, the processor/controller 20 executesimage processing routines to determine the size of the testee's pupil ineach frame. One way to accomplish this is by counting the number ofpixels that correspond to the testee's pupil in each frame.

Some suitable approaches for evaluating the testee's pupil dilationresponse are described in Best Practices and Advice for UsingPupillometry to Measure Listening Effort: An Introduction for Those WhoWant to Get Started, Mathew B. WINN, et al., Trends Hear. 2018January-December; 22: 2331216518800869 (Sep. 28, 2018), which isincorporated herein by reference in its entirety. Alternative approacheswill be apparent to persons skilled in the relevant art.

In certain situations described below, it can be beneficial to increasethe illumination that arrives at the testee's eyes. A monitor 35 oranother illumination source (e.g., a floor lamp) may be provided forthis purpose. For example, the level of illumination that arrives at thetestee's pupil could be increased using a conventional computer monitor35, and having the processor/controller 20 send appropriate signals tothe monitor 35 to display a bright background. Alternatively, inembodiments that rely on a floor lamp (not shown) to provideillumination, the processor/controller 20 could send a signal to turn ona smart outlet into which the floor lamp is plugged.

FIG. 2 depicts a flowchart for an embodiment in which a set of sentencesis presented to the testee, and the system evaluates whether the testeeis being deceptive by monitoring changes in the determined size of thetestee's pupil. The steps S12-S16 of this flowchart are implemented byan appropriate program or programs running on the processor/controller20 depicted in FIG. 1.

First, in step S12, the processor/controller 20 controls the audiocircuit 30 so that the audio circuit outputs an audio signalcorresponding to a set of sentences. The speaker 32 converts the audiosignal to sounds that are presented to the testee. The set of sentencesincludes an initial sentence, a first-type sentence, and a plurality ofsecond-type sentences. The sentences can be in the form of questions,statements, or any other form. In some embodiments, the first-typesentence and each of the plurality of second-type sentences are binaryquestions. As used herein, a “binary question” is a question that hasonly two possible answers (e.g., yes or no; true or false; etc.).

A “first-type sentence” is a sentence that the party administering thetest cares about, and the evaluation of whether a testee is beingdeceptive applies to the first-type sentence. The “second-typesentence(s)” and optional “third-type sentence(s)” described below arepresented to the testee so that the system has a baseline against whichto compare the testee's response to the first-type sentence, with theultimate goal of evaluating whether the testee is being deceptive withrespect to the first-type sentence.

The first-type sentence is expected to evoke significant pupil dilationin a testee who is being deceptive and not to evoke significant pupildilation in a testee who is not being deceptive. Each of the second-typesentences is not expected to evoke significant pupil dilation in thetestee (although pupil dilation may, in fact, occur, depending on thecontent of the sentence for specific individuals).

Typically, a party that wants to detect deception is interested in aparticular topic or a set of topics. Topics of interest could span awide variety of subjects. Examples include (a) whether a person who isabout to board an airplane is carrying explosives; (b) whether aparticular person stole a particular item (e.g., a bracelet); and (c)whether a visitor to a prison is carrying contraband; etc.

The content of the first-type sentence is selected (before the testingbegins) so that it relates to the specific topic in which the partyadministering the test is interested. Assume, for example, that thetopic of interest is item (a) listed above. In this situation, thefirst-type sentence could be “do you have any explosives?” Presumably,any person carrying explosives onto an airplane would want to concealthat fact. As a result, asking that person “do you have any explosives?”will create a cognitive and/or emotional response in that person. Andthis cognitive and/or emotional response will give rise to an associatedpupil-dilation response. On the other hand, asking the same question toan innocent person will not create a cognitive and/or emotional responseand will therefore not evoke a significant pupil dilation in theinnocent person. In another example, the question “did you steal abracelet?” is expected to evoke significant pupil dilation in a testeewho is being deceptive (i.e., in a testee who has stolen a bracelet),and not to evoke significant pupil dilation in testees who are not beingdeceptive (i.e., in testees who have not stolen a bracelet).

The content of the second-type sentences is selected so that it is notexpected to evoke significant pupil dilation in the testee. Examplesinclude pointed sentences of which the testee is not guilty such as “didyou steal a passport?” (when the testee has not, in fact, stolen apassport). Other examples include innocuous questions like “do you haveany shirts in your suitcase?” or “what's the weather like outside?”.Preferably, care is taken in formulating the content of second-typesentences to minimize the following responses from the testee: memoryprocessing; linguistic processing; recognition; computationalprocessing; emotional responses (e.g., fear, stress, relaxation, happy,love); after thoughts; familiarity; interest/non-interest; surprise;embarrassment; confusion; amazement; laughter; anger; relief; a desireto comply. etc. Minimizing all of these responses from the testee willcorrespondingly minimize any impact on the testee's pupil-dilationresponse. Note that while the content of the second-type sentences isnot expected to evoke significant pupil dilation, in certain situationsthe second-type sentences will, in fact, evoke a significant pupildilation. This will depend on the content of the second-type sentenceand the individual testee. But the pupil-dilation response induced bythe second-type sentences is expected to be smaller than thepupil-dilation response induced by the first-type sentence for deceptivetestees. Thus, the deceptive testee will be detected correctly even inthese cases, and the non-deceptive testees will also be detectedcorrectly.

One example where this FIG. 2 embodiment would be useful is in thecontext of a bar that wants to screen incoming people in a state wherethe minimum drinking age is 21. In this situation, the partyadministering the test (i.e., the bar) is only interested in whether theID that is being presented by each person attempting to enter the bar isgenuine or fake. For this situation, the first-type sentence would be“do you have a fake ID?”; and a suitable sequence of questions for thissituation would be as follows: (1) Are you meeting a friend? (2) Do youhave a fake ID? (3) Did you arrive by car? (4) did you bring a camera?In this example, question #1 is the initial sentence 51; question #2 isthe first-type sentence 55; and questions #3 and 4 are the second-typesentences 52.

In some situations, the set of sentences may contain more than onefirst-type sentence. Assume, for example, that an airline wants toscreen people who are about to board a plane. In this situation, theparty administering the test needs to know whether each person iscarrying any of the following items: guns, knives, explosives, andflammable liquids. For this situation, the following sequence ofquestions would be suitable: (1) Are you bringing any shirts on board?(2) Are you bringing any guns on board? (3) Are you bringing any food onboard? (4) Are you bringing any knives on board? (5) Are you bringingany explosives on board? (6) Are you bringing a camera on board? (7) Areyou bringing any flammable liquids on board? In this example, question#1 is the initial sentence 51; questions #2, 4, 5, and 7 are thefirst-type sentences 55; and questions #3 and 6 are the second-typesentences 52.

FIG. 3 depicts an example of a time sequence for presenting the set ofsentences to the testee. More specifically, the initial sentence 51 isoutput prior to the first-type sentence 55 and the plurality ofsecond-type sentences 52. But as between the first-type sentence and thesecond-type sentences 52, the sequence is not critical. Note that in theexample depicted in FIG. 3, there is only a single first-type sentence55 and only two second-type sentences 52. But in alternative examples,there could be more than one first-type sentence, and/or more than twosecond-type sentences.

Notably, the inventor has determined that the probability of success inevaluating whether a testee is being deceptive can be improvedsignificantly by making the first-type sentence 55 and the second-typesentences 52 similar to each other in a number of important regards.More specifically, (1) the first-type sentence and each of thesecond-type sentences should all be in the same language (i.e., all ofthe sentences could be in English; or all of the sentences could be inFrench); (2) the average volume of each of the second-type sentencesshould be within 10 dB of the average volume of the first-type sentence;and (3) the first-type sentence and each of the second-type sentencesshould have a duration of less than 5 s.

Making the first-type sentence each of the second-type sentences similarto each other in these ways increases the probability that thepupil-dilation response observed by the system is attributable to thecontent of those sentences as opposed to other factors including but notlimited to cognitive load, emotional load, etc. And this canadvantageously increase the probability of success in evaluating whethera testee is being deceptive.

Optionally, the first-type sentence 55 and the second-type sentences 52may be made similar to each other in additional ways, which can furtherimprove the probability of success in evaluating whether a testee isbeing deceptive. In some embodiments, this is accomplished by making thegrammatical structure and duration of each of the second-type sentencessimilar to the grammatical structure and duration of the first-typesentence; using similar tones for the first-type sentence and each ofthe second-type sentences; and/or outputting the first-type sentence andeach of the second-type sentences in a similar voice. Optionally, thefirst-type sentence 55 in the second-type sentences 52 may be madesimilar to each other in the level of complexity and language style(e.g., modern American English vs. modern British English vs.Shakespearean English vs. New York slang). They may also be made similarto each other in duration, the number of words per sentence (e.g., lessthan 9 words per sentence). The peak volume of each of the second-typesentences may optionally also be set to be within 10 dB of the peakvolume of the first-type sentence. Making the first-type sentence eachof the second-type sentences similar to each other in one or more ofthese additional ways can further increases the probability that thepupil-dilation response observed by the system is attributable to thecontent of those sentences as opposed to other factors, which canfurther increase the probability of success in evaluating whether atestee is being deceptive.

In some embodiments, the first-type sentence 55 and the second-typesentences 52 are all true/false statements. In some embodiments, thefirst-type sentence 55 and the second-type sentences 52 are all binaryquestions.

FIG. 4 depicts yet another optional way to make the first-type sentence55 and the second-type sentences 52 similar to each other. This isaccomplished by incorporating a keyword into each of those sentences,and positioning all of the keywords at a similar location within eachsentence. The keyword is the critical word in the sentence. In manycases, the keyword will be the object of the sentence. The first-typesentence 55 includes a material keyword 65, and each of the second-typesentences 52 includes a respective other keyword 62, and the position ofthe respective other keyword 62 within each of the second-type sentences52 is similar to the position of the material keyword 65 within thefirst-type sentence 55.

FIG. 4 depicts an example of presenting a set of sentences 51-55 to atestee, where each of the sentences 52-55 includes a respective keyword62-65. Assume, for example, that a bracelet has been stolen, and thatthe party administering the test suspects a particular person ofstealing the bracelet. In this situation, “did you steal a bracelet?”would be the first-type sentence 55, and the other two options (i.e.,“did you steal a pencil?” and “did you steal a passport?”) would be thesecond-type sentences 52. Also, in this situation, the word “bracelet”would be the keyword 65 of the first-type sentence 55; and the words“pencil” and “passport” would be the keywords 62 of the second-typesentences 52.

To evaluate positional similarity, any two given keywords are deemed tohave a similar position within a respective sentence when the two givenkeywords are either (a) both positioned in the initial one-third of therespective sentence, (b) both positioned in the middle one-third of therespective sentence, or (c) both positioned in the last one-third of therespective sentence. For example, in FIG. 4, the material keyword 65(“bracelet”) is positioned in the last one-third of the first-typesentence 55; and the two other keywords 62 (“pencil” and “passport”) arealso each positioned in the last one-third of the respective second-typesentence 52. All three of those keywords therefore have a similarposition within their respective sentence. (The portions of eachsentence that correspond to each one-third are demarcated by the labelson the bottom of FIG. 4 and the dashed vertical lines.) Maintainingconsistency of the positions of the various keywords within therespective sentences provides a significant improvement in theprobability of success in evaluating whether a testee is beingdeceptive. Making the first-type sentence each of the second-typesentences similar to each other in this additional way can furtherincreases the probability that the pupil-dilation response observed bythe system is attributable to the content of those sentences as opposedto other factors, which can further increase the probability of successin evaluating whether a testee is being deceptive.

Gaps are interposed between adjacent sentences 52, 55, as depicted inFIG. 3. Preferably, the gaps are at least 3 s long. In some embodiments,these gaps will all have the same duration. But in other embodiments,the size of the gaps may vary. In some embodiments the gap can also becalculated dynamically to improve performance. In these embodiments, thegap should be long enough to (a) make sure the previous response to theprevious sentence is over and (b) make sure that the pupil is contractedenough for the system to detect dilation in response to a new sentence.Condition (b) may be determined by waiting until the pupil size is lessthan the median of the pupil size of a specific testee. The median canbe calculated in a window including the previous pupil size during aquestion and response, or it can be calculated on the entire pupilresponse until the current time. Other estimations for a small enoughpupil are possible. In addition, the shortest gap that fulfills theserequirements may be selected, so the test will as short as possible.

In some embodiments, the entire set of sentences is preferably output inless than 2 minutes, and the set of sentences that is output preferablycontains between 4-10 sentences.

Returning to FIG. 4, the first-type sentence 55 “did you steal abracelet?” is expected to evoke significant pupil dilation in a testeewho is being deceptive (i.e., in a testee who has stolen a bracelet),and not to evoke significant pupil dilation in a testee who is not beingdeceptive (i.e., in a testee who has not stolen a bracelet). Each of thesecond-type sentences 52 (i.e., “did you steal a pencil?” and “did yousteal a passport?”) is not expected to evoke significant pupil dilationin the testee (assuming we know in advance that the testee has not, infact, stolen those items).

FIG. 5 depicts one example of the changes in pupil size over time for atestee who is telling the truth (lower trace 70T) and for a testee whois being deceptive (upper trace 70D) in response to a sequence ofsentences that includes an initial sentence 51, followed by 4second-type sentences 52, followed by a first-type sentence 55, followedby one second-type sentence 52. The portions of each of the traces 70Dand 70T that correspond to each of these sentences are demarcated by thelabels on the bottom of FIG. 5 and the dashed vertical lines, and thelarge solid dots represent the start of the respective sentence. The Xaxes in FIG. 5 corresponds to time in seconds; and the Y axes in FIG. 5corresponds to pupil size (measured in pixels). Traces 70D and 70Trepresent the measured pupil-sized data (after some preprocessingincluding low-pass filtering), and traces 75D and 75T represent therespective corresponding moving averages of the same data. These movingaverages may be calculated, for example, by averaging the previous Nsamples, where N is an integer between 3 and 12. One suitable approachfor evaluating the testee's pupil dilation response in all embodimentsdescribed herein is to measure the percentage increase in this movingaverage during the interval of time that corresponds to each sentence orword (depending on the context). In some embodiments, the moving averageis calculated by averaging the previous 6 samples.

A testee's pupils will typically dilate significantly in response to theinitial sentence 51 in any sequence, regardless of the content of thatinitial sentence. Accordingly, the pupil-size data that corresponds tothe initial sentence is not used to evaluate whether the testee is beingdeceptive.

An examination of trace 75D for the deceptive testee reveals that thepercentage increase in pupil size during the interval of time thatcorresponds to the first-type sentence 55 is larger than the percentageincrease in pupil size during any of the intervals of time thatcorrespond to the second-type sentences 52. In numeric terms, the movingaverage of the deceptive testee's pupil size increased about 35% (i.e.,from 800 to 1100) in the interval of time that corresponds to thefirst-type sentence 55. But during each of the intervals of time thatcorrespond to the second-type sentences 52, the increase in the movingaverage of the deceptive testee's pupil size was always less than 15%.Because the pupil-dilation response to the first-type sentence 55 islarger than the pupil-dilation response to each of the plurality ofsecond-type sentences 52 for a deceptive testee, the system can use thisrelationship to evaluate whether a testee is being deceptive. Forexample, the system can (a) conclude that a testee's response to thefirst-type sentence 55 is deceptive when the system recognizes that thepupil-dilation response to the first-type sentence 55 is larger than thepupil-dilation response to each of the plurality of second-typesentences 52; and (b) conclude that a testee's response to thefirst-type sentence 55 is not deceptive when the pupil-dilation responseto the first-type sentence 55 is not larger than the pupil-dilationresponse to each of the plurality of second-type sentences 52.

On the other hand, an examination of trace 75T for the truthful testeereveals that the percentage increase in pupil size during the intervalof time that corresponds to the first-type sentence 55 is not largerthan the percentage increase in pupil size during any of the intervalsof time that correspond to the second-type sentences 52. In numericterms, the increase in the moving average of the truthful testee's pupilsize was less than 15% for the first-type sentence 55 and also for allof the second-type sentences 52. The system can therefore conclude thata testee's response to the first-type sentence 55 is truthful/notdeceptive when the system recognizes that the pupil-dilation response tothe first-type sentence 55 is not larger than the pupil-dilationresponse to the second-type sentences 52.

Returning now to FIGS. 1 and 2 (and, more specifically, to step S12 inFIG. 2), the processor/controller 20 monitors changes in the determinedsize of the testee's pupil during the outputting of the first-typesentence and the plurality of second-type sentences and during anyresponses to the first-type sentence and the plurality of second-typesentences made by the testee. As noted above, the processor/controller20 executes image processing routines to determine the size of thetestee's pupil in each frame of the images that include the testee'spupil.

In step S14, the processor/controller 20 compares changes in thedetermined size of the testee's pupil in response to the first-typesentence with changes in the determined size of the testee's pupil inresponse to the second-type sentences to ascertain whether apupil-dilation response to the first-type sentence is larger than thepupil-dilation response to each of the plurality of second-typesentences. Based on this ascertaining, the processor/controller 20outputs an indication of deceptiveness or non-deceptiveness in step S16.This may be accomplished, for example, by (a) outputting an indicationof deceptiveness when the processor/controller 20 ascertains that thepupil-dilation response to the first-type sentence is larger than thepupil-dilation response to each of the plurality of second-typesentences, and/or (b) outputting an indication of non-deceptiveness whenthe processor/controller 20 ascertains that the pupil-dilation responseto the first-type sentence is not larger than the pupil-dilationresponse to each of the plurality of second-type sentences.

When more than one first-type sentence is included in the set ofsentences, the processor/controller 20 compares changes in thedetermined size of the testee's pupil in response to each of thefirst-type sentence with changes in the determined size of the testee'spupil in response to the second-type sentences to ascertain whether apupil-dilation response to each individual first-type sentence is largerthan the pupil-dilation response to each of the plurality of second-typesentences. Based on this ascertaining, the processor/controller 20preferably outputs a respective indication of deceptiveness ornon-deceptiveness for each individual first-type sentence.

The embodiments described herein rely on detecting a pupil-dilationresponse. But in situations where a testee's pupil is already verydilated, distinguishing the amount of dilation that results from thefirst-type sentence 55 from the amount of dilation that results from thesecond-type sentences 52 may be difficult. In these situations, it ispreferable to activate a light source that increases the level ofillumination that arrives at the testee's pupil. This will cause thetestee's pupil to contract. After the testee's pupil has contracted, alarger amount of dilation will be possible. And this larger amount ofdilation will make it easier to distinguish the amount of dilation thatresults from the first-type sentence 55 from the amount of dilation thatresults from the second-type sentences 52.

In some embodiments, the increase in illumination may persist for theduration of the testing session. This may be achieved, for example byhaving the processor/controller 20 send signals to the monitor 35 thatcause the monitor 35 to display a bright image (see FIG. 1). in anotherexample, the increase in illumination may be achieved by having theprocessor/controller 20 send signals (e.g., via Wi-Fi) to a smart outlet(not shown) into which a floor lamp has been plugged. When the smartoutlet turns on, the floor lamp will turn on, which will increase thelevel of illumination that arrives at the testee's pupil.

In other embodiments, the increase in illumination may be transient.This may be achieved, for example by having the processor/controller 20send signals to the monitor 35 that cause the monitor 35 to flash ashort duration bright image (e.g., between 0.1 and 0.5 s) just prior tothe time a given sentence is presented to the testee.

The embodiments described above in connection with FIG. 3-5 utilizes twodifferent sentence types to evaluate whether a testee is beingdeceptive. More specifically, these examples utilize (1) a first-typesentence that is expected to evoke significant pupil dilation in atestee who is being deceptive and not to evoke significant pupildilation in a testee who is not being deceptive, and (2) second-typesentences that are not expected to evoke significant pupil dilation inthe testee. (The initial sentence is not relied on to evaluate whether atestee is being deceptive.) The embodiments described below inconnection with FIG. 6-7 utilize these same two sentence types plus onethird-type sentence type (referred to herein as an “third-typesentence”) to evaluate whether or not a testee is being deceptive. Thethird-type sentence is expected to evoke significant pupil dilation in atestee who is not being deceptive. The third-type sentence may alsoevoke a response in deceptive testees, but in this case the pupildilation response to first-type sentence will larger than the pupildilation response to third-type sentence. And as described below, thethird-type sentence improves the confidence of the evaluations made bythe system both for determinations that a testee is being deceptive andfor determinations that a testee is not being deceptive.

FIG. 6 depicts an example of a time sequence for presenting the set ofsentences to the testee in these embodiments. More specifically, theinitial sentence 51 is output prior to the first-type sentence 55, theplurality of second-type sentences 52, and the third-type sentence 58.But as between the latter three types 55, 52, and 58, the sequence isnot critical. Note that in the example depicted in FIG. 6, there is onlya single first-type sentence 55, only two second-type sentences 52, andonly one third-type sentence 58. But in alternative examples, therecould be more than one first-type sentence, more than two second-typesentences, and/or more than one third-type sentence.

Similar to the situation described above in connection with FIG. 5, thepupil-size data that corresponds to the initial sentence 51 is not usedto evaluate whether the testee is being deceptive in this FIG. 6-7embodiment.

The nature and content of the initial sentence 51, the first-typesentence 55, each of the second-type sentences 52, and theinterrelationship between those types of sentences in this FIG. 6-7embodiment is the same as described above in connection with FIG. 3-5.But notably, the language, grammatical structure, duration, volume,tone, voice, complexity, and language style of the third-type sentencedoes not have to be similar to the first-type sentence. If thethird-type sentence has a keyword, the position of the keyword does nothave to be similar to the position of the keyword in the first-typesentence. Furthermore, the third-type sentence may not even have akeyword at all.

The main requirement of the third-type sentence is that it should evokesignificant pupil dilation in a testee who is not being deceptive. Thethird-type sentence may or may not evoke significant pupil dilation in atestee who is being deceptive. One example of a suitable third-typesentence is a sentence that is output in a different language than allthe first-type and second-type sentences. For example, in a situationwhere the first-type sentence and all the second-type sentences areoutput in English, the third-type sentence could be output in German.The German sentence will induce more cognitive load than the Englishsentences, and will therefore cause a larger pupil size response from anon-deceptive testee (as compared to the first-type and second-typesentences). Another example of a suitable third-type sentence is asentence that is significantly louder than the first-type sentence andall the second-type sentences. The louder sentence will increase thetestee's emotional load, and will therefore cause a larger pupil sizeresponse from a non-deceptive testee (as compared to the first-type andsecond-type sentences). Yet another example of a suitable third-typesentence is a sentence that is expected to evoke significant pupildilation based on its content. Examples of content that can evokesignificant pupil dilation include absurd statements (e.g., “why aren'tyou wearing underpants today?”), insults (e.g., “your shirt isexceptionally ugly”), jokes, etc. The content will increase the testee'semotional load, and will therefore cause a larger pupil size responsefrom a non-deceptive testee (as compared to the first-type andsecond-type sentences).

When third-type sentence is presented to a deceptive testee, it may alsoevoke significant pupil dilation. But because the deceptive testee'sresponse to the first-type sentence actually has consequences (e.g.,getting arrested, not getting a job, etc.), their pupil dilationresponse to the first-type sentence is expected to be larger than theirpupil dilation response to the third-type sentence. Note that in somecases, particularly when the third-type sentence arrives after thefirst-type sentence, the third-type sentence may not evoke significantpupil dilation in a deceptive testee.

FIG. 7 depicts one example of the changes in pupil size over time for atestee who is telling the truth (lower trace 80T) and for a testee whois being deceptive (upper trace 80D) in response to a sequence ofsentences that includes an initial sentence 51, followed by a first-typesentence 55, two second-type sentences 52, followed by a third-typesentence 58, followed by one second-type sentence 52. The portions ofeach of the traces 80D and 80T that correspond to each of thesesentences are demarcated by the labels on the bottom of FIG. 7 and thedashed vertical lines. The X axes in FIG. 7 corresponds to time inseconds; and the Y axes in FIG. 7 correspond to pupil size (measured inpixels). Traces 80D and 80T represent the measured pupil-sized data(after some preprocessing including low-pass filtering), and traces 85Dand 85T represent the respective corresponding moving averages of thesame data, which may be calculated using any of the approaches describedabove in connection with FIG. 5. The difference in scale of the Y axes(between the lower traces 80T/85T and the upper traces 80D/80T) isattributable to the different pupil sizes of two different individualtestees.

The third-type sentence 58 that is added in the FIG. 6-7 embodiments canprovide an advantage with respect to the FIG. 3-5 embodiments byimproving the confidence of the evaluations made by the system, both fordeterminations that a testee is being deceptive and for determinationsthat a testee is not being deceptive.

Improving the confidence of evaluations in those situations where thetestee is being deceptive is best understood by comparing trace 75D inFIG. 5 (which does not include a third-type sentence) with trace 85D inFIG. 7 (which does include a third-type sentence). In these FIG. 6-7embodiments, the processor/controller 20 compares changes in thedetermined size of the testee's pupil in response to the first-typesentence 55 with changes in the determined size of the testee's pupil inresponse to the second-type sentences 52. This is done to ascertainwhether a pupil-dilation response to the first-type sentence 55 islarger than the pupil-dilation response to each of the plurality ofsecond-type sentences 52 (which is the case for trace 80D depicted inFIG. 7). So far, this is similar to the FIG. 3-5 embodiment. But inaddition, the processor/controller 20 in the FIG. 6-7 embodimentscompares changes in the testee's pupil size in response to thethird-type sentence 58 with changes in the testee's pupil size inresponse to the first-type sentence 55. This is done to ascertainwhether a pupil-dilation response to the first-type sentence 55 islarger than a pupil-dilation response to the third-type sentence 58(which is also the case for trace 80D).

In the FIG. 6-7 embodiments, an output indicating deceptiveness isgenerated when the processor/controller 20 ascertains that apupil-dilation response to the first-type sentence 55 is larger than thepupil-dilation response to each of the plurality of second-typesentences 52 and also larger than the pupil-dilation response to thethird-type sentence 58 (which is the case for trace 80D). Theseembodiments advantageously improve the confidence of a “deceptiveness”output with respect to the confidence of the FIG. 3-5 embodimentsdiscussed above. larger pupil-dilation response to the first-typesentence 55 as compared to the third-type sentence 58 is expected from adeceptive testee because the first-type sentence is expected to have astronger impact on a deceptive testee than the third-type sentence. Thisstronger impact is expected because there will usually be significantand/or unpleasant consequences associated with deception with regard tothe first-type sentence (e.g., shame, failure, being charged with acrime, not getting a job, etc.).

Improving the confidence of evaluations in those situations where thetestee is not being deceptive is best understood by comparing trace 75Tin FIG. 5 (which does not include a third-type sentence) with trace 85Tin FIG. 7 (which does include a third-type sentence). More specifically,an examination of trace 85T for the truthful testee reveals that thepercentage increase in pupil size during the interval of time thatcorresponds to the third-type sentence 58 is larger than the percentageincrease in pupil size during any of the intervals of time thatcorrespond to the second-type sentences 52, and is also larger than thepercentage increase in pupil size during the first-type sentenceinterval 55.

In these FIG. 6-7 embodiments, in addition to comparing the responses tothe first-type sentence to the responses to the second-type sentences(as described above), the processor/controller 20 also compares changesin the testee's pupil size in response to the third-type sentence 58with changes in the testee's pupil size in response to the first-typesentence 55. An output indicating non-deceptiveness is generated wheneither (i) the processor/controller 20 ascertains that a pupil-dilationresponse to the third-type sentence 58 is larger than the pupil-dilationresponse to the first-type sentence 55 (which is the case for trace80T), or (ii) when the processor/controller 20 ascertains that thepupil-dilation response to the first-type sentence is not larger thanthe pupil-dilation response to each of the plurality of second-typesentences. (Condition (ii) is similar to the situation described abovein connection with FIGS. 2-5.) These embodiments advantageously improvethe reliability of a “non-deceptiveness” output with respect to the FIG.3-5 embodiments discussed above.

The embodiments described above in connection with FIGS. 1-7 include atleast one “first-type sentence” (which is a sentence that the partyadministering the test cares about) and a plurality of “second-typesentences” which are used as a baseline against which to compare thetestee's response to the first-type sentence.

FIGS. 8 and 9 depict an example that relies on a different approach forevaluating whether a testee is being deceptive. In this approach, theset of sentences that is presented includes at least three first-typesentences. As in the FIG. 1-7 embodiments, each of the first-typesentences is expected to evoke significant pupil dilation in a testeewho is being deceptive and not to evoke significant pupil dilation in atestee who is not being deceptive. But notably, this embodiment does notrequire any second-type sentences to evaluate whether a testee is beingdeceptive. In these embodiments, the set of sentences includes aninitial sentence 51 and at least three first-type sentences 55. Theinitial sentence 51 is output prior to all of the first-type sentences55.

Assume, for example, that a customs agent wants to screen people who areabout to enter a country. In this situation, the party administering thetest could ask the following questions: (1) What flight did you arriveon? (2) Did you bring any fruits or vegetables? (3) Did you bring anyplants or seeds? (4) Did you bring any animals or insects? (5) Have yourecently been on a farm or ranch? (6) Are you carrying more than $10,000in currency? (7) Did you bring any cigarettes with you? (8) Did youbring any alcoholic beverages? (9) Did you bring any drugs? In thissituation, the customs agent presumably cares about whether the testeeis being deceptive in response to questions #2-9, and wants to evaluatewhether the testee is being deceptive for all those questions.Therefore, in this example, question #1 is the initial sentence 51, andall of the other questions #2-9 qualify as first-type sentences 55.

When the number of questions is sufficiently large, it is reasonable toassume that the answer to at least two of the questions will truthfullybe “no,” and for those questions, significant pupil dilation is notexpected to be evoked in the testee. In this situation, the testee'snon-deceitful responses serve as the baseline against which the testee'sresponse to the other questions are compared. One suitable approach forselecting the sentences that will be used as a baseline for comparisonis to evaluate the pupil-dilation response to each of the sentences, andselect the two sentences that give rise to the smallest pupil-dilationresponse as a baseline against which the remaining pupil-dilationresponses will be compared. For the remaining questions, evocation ofsignificant pupil dilation is expected if the testee is being deceptiveand not expected if the testee is not being deceptive.

The FIG. 1 hardware block diagram and the description of that figureabove applies with equal force to this FIG. 8-9 embodiment.

The probability of success in evaluating whether a testee is beingdeceptive can be improved significantly by making the first-typesentences 55 similar to each other in a number of important regards.More specifically, the first-type sentences are all in the samelanguage; their average volumes are all within 10 dB of each other; andeach of them has a duration of less than five seconds. Optionally, eachof the first-type sentences 55 may be made similar to each other inadditional ways (e.g., as described above in connection with the FIG.1-7 embodiments).

Gaps of at least three seconds are interposed between adjacent sentences(e.g., as described above in connection with the FIG. 1-7 embodiments).

Turning now to FIG. 8, in step S32 the set of sentences 51-55 ispresented to the testee, and the system evaluates whether the testee isbeing deceptive by monitoring changes in the determined size of thetestee's pupil (e.g., using an appropriate program or programs runningon the processor/controller 20 depicted in FIG. 1).

The processor/controller 20 controls the audio circuit 30 so that theaudio circuit outputs an audio signal corresponding to a set ofsentences. The speaker 32 converts the audio signal to sounds that arepresented to the testee. The set of sentences includes an initialsentence, and at least three first-type sentences. The sentences can bein the form of questions, statements, or any other form.

As described above in connection with the FIG. 1-7 embodiments, a“first-type sentence” is a sentence that the party administering thetest cares about, and the evaluation of whether a testee is beingdeceptive applies to the first-type sentences. Each first-type sentenceis expected to evoke significant pupil dilation in a testee who is beingdeceptive and not to evoke significant pupil dilation in a testee who isnot being deceptive.

The processor/controller 20 monitors changes in the determined size ofthe testee's pupil during the outputting of the first-type sentences andduring any responses to the first-type sentences made by the testee. Theprocessor/controller 20 executes image processing routines to determinethe size of the testee's pupil in each frame of the images that includethe testee's pupil.

In step S34, The processor/controller 20 compares changes in thedetermined size of the testee's pupil in response to each of thefirst-type sentences to ascertain whether a pupil-dilation response toeach respective one of the first-type sentences is at least 10% largerthan a pupil-dilation response to at least two of the other first-typesentences.

Based on this ascertaining, in step S36 the processor/controller 20outputs an indication of deceptiveness or non-deceptiveness for at leastone of the first-type sentences. This may be accomplished, for example,by (a) outputting an indication of deceptiveness for a respective one ofthe first-type sentences when the processor/controller 20 ascertainsthat the pupil-dilation response to the respective first-type sentenceis at least 10% larger than a pupil-dilation response to at least two ofthe other first-type sentences, and/or (b) outputting an indication ofnon-deceptiveness when the processor/controller 20 ascertains that nopupil-dilation response to any given one of the first-type sentences isat least 10% larger than a pupil-dilation response to at least two ofthe other first-type sentences.

Optionally, this FIG. 8-9 embodiment may also utilize a third-typesentence to improve the confidence of the evaluations made by thesystem. The third-type sentence in this FIG. 8-9 embodiment is similarto the third-type sentence described above in the FIG. 1-7 embodiment,and it is expected to evoke significant pupil dilation in a testee whois not being deceptive.

When the optional third-type sentence is utilized, in addition tocomparing the responses to the first-type sentences (as describedabove), the processor/controller 20 also compares changes in thetestee's pupil size in response to the third-type sentence with changesin the testee's pupil size in response to each of the first-typesentences. The processor/controller 20 outputs an indication ofdeceptiveness for a respective one of the first-type sentences when theprocessor/controller 20 ascertains that the pupil-dilation response tothe respective first-type sentence is at least 10% larger than thepupil-dilation response to at least two of the other first-typesentences and is also larger than the pupil-dilation response to thethird-type sentence. The processor/controller 20 outputs an indicationof non-deceptiveness when the processor/controller 20 ascertains thatthe pupil-dilation response to each of the first-type sentences issmaller than the pupil-dilation response to the third-type sentence, orwhen the processor/controller 20 ascertains that the pupil-dilationresponse to none of the first-type sentences is at least 10% larger thanthe pupil-dilation response to at least two other first-type sentences.

In the embodiments described above in connection with FIG. 1-9, a set ofsentences (e.g., questions) are presented to the testee, and changes inthe testee's pupil size are monitored. The embodiments described belowin connection with FIG. 10-11 are similar, but instead of presenting aset of sentences, a set of words are presented to the testee. The FIG. 1hardware block diagram applies with equal force to the FIG. 10-11embodiments.

FIG. 10 depicts a flowchart for an embodiment in which a set of words ispresented to the testee, and the system evaluates whether the testee isbeing deceptive by monitoring changes in the determined size of thetestee's pupil. The steps S20-S26 of this flowchart are implemented byan appropriate program or programs running on the processor/controller20 depicted in FIG. 1.

First, in step S20, the processor/controller 20 controls the audiocircuit 30 so that the audio circuit outputs an audio signalcorresponding to an introductory phrase or sentence. The speaker 32converts the audio signal to sounds that are presented to the testee.When an introductory sentence is used, it could be a question (e.g.,“What do you think of the following things?) or a statement (e.g., “Weare going to monitor your reaction to the following items”).

Next, in step S22, the processor/controller 20 controls the audiocircuit 30 so that the audio circuit outputs an audio signalcorresponding to a set of words. The speaker 32 converts the audiosignal to sounds that are presented to the testee. The set of wordsincludes an initial word, a first-type word, and a plurality ofsecond-type words.

A “first-type word” is a word that the party administering the testcares about, and the evaluation of whether a testee is being deceptiveapplies to the first-type word. The “second-type word(s)” and“third-type word(s)” described below are presented to the testee so thatthe system has a baseline against which to compare the testee's responseto the first-type word, with the ultimate goal of evaluating whether thetestee is being deceptive with respect to the first-type word. Thefirst-type word, the second-type word, and third-type word correspond tothe first-type sentence, second-type sentence, and third-type sentencein the FIG. 2-9 embodiments described above, but the former are wordsinstead of sentences.

The first-type word is expected to evoke significant pupil dilation in atestee who is being deceptive and not to evoke significant pupildilation in a testee who is not being deceptive. Each of the second-typewords is not expected to evoke significant pupil dilation in the testee(although pupil dilation may, in fact, occur, depending on the contentof the word).

FIG. 11 depicts an example of a time sequence for presenting the set ofwords to the testee. More specifically, the introductory sentence 150 ispresented first. Then, the initial word 151 is output prior to thefirst-type word 155 and the plurality of second-type words 152. But asbetween the first-type word and the second-type words 152, the sequenceis not critical. Note that in the example depicted in FIG. 11, there aretwo first-type words 155 and three second-type words 152. But inalternative examples, there could be a different number of first-typewords and/or second-type words.

Gaps of at least 2 s interposed between words within the set. In someembodiments, these gaps will all have the same duration. But in otherembodiments, the size of the gaps may vary (e.g., as described above inconnection with the FIG. 1-9 embodiment). The entire set of words ispresented to the testee in less than 2 minutes, and the set of wordscontains less than 20 words.

As in the embodiment described above in connection with FIG. 1-9, theprobability of success in evaluating whether a testee is being deceptivecan be improved significantly by making the first-type word 155 and thesecond-type words 152 similar to each other in a number of importantregards. More specifically, the first-type word and each of thesecond-type words should all be in the same language (i.e., all of thewords could be in English; or all of the words could be in French); andthe average volume of each of the second-type words should be within 10dB of the average volume of the first-type word.

Making the first-type word each of the second-type words similar to eachother in these ways increases the probability that the pupil-dilationresponse observed by the system is attributable to the content of thosewords as opposed to other factors including but not limited to cognitiveload, emotional load, etc. And this can advantageously increase theprobability of success in evaluating whether a testee is beingdeceptive.

Optionally, the first-type word 155 and the second-type words 152 may bemade similar to each other in additional ways, which can further improvethe probability of success in evaluating whether a testee is beingdeceptive. In some embodiments, this is accomplished by outputting thefirst-type word and each of the second-type words in the same voiceand/or making them similar to each other in the level of complexity andlanguage style. The peak volume of each of the second-type words mayoptionally also be set to be within 10 dB of the peak average volume ofthe first-type word. Making the first-type word each of the second-typewords similar to each other in one or more of these additional ways canfurther increases the probability that the pupil-dilation responseobserved by the system is attributable to the content of those words asopposed to other factors, which can further increase the probability ofsuccess in evaluating whether a testee is being deceptive.

Returning now to FIGS. 10 and 11 (and, more specifically, to step S22 inFIG. 10), the processor/controller 20 monitors changes in the determinedsize of the testee's pupil during the outputting of the first-type wordand the plurality of second-type words and during any responses to thefirst-type word and the plurality of second-type words made by thetestee. As noted above, the processor/controller 20 executes imageprocessing routines to determine the size of the testee's pupil in eachframe of the images that include the testee's pupil.

In step S24, the processor/controller 20 compares changes in thedetermined size of the testee's pupil in response to the first-type wordwith changes in the determined size of the testee's pupil in response tothe second-type words to ascertain whether a pupil-dilation response tothe first-type word is larger than the pupil-dilation response to eachof the plurality of second-type words. Based on this ascertaining, theprocessor/controller 20 outputs an indication of deceptiveness ornon-deceptiveness in step S26. This may be accomplished, for example, by(a) outputting an indication of deceptiveness when the pupil-dilationresponse to the first-type word is larger than the pupil-dilationresponse to each of the plurality of second-type words, and/or (b)outputting an indication of non-deceptiveness when the pupil-dilationresponse to the first-type word is not larger than the pupil-dilationresponse to each of the plurality of second-type words.

Optionally, a light source that increases the level of illumination thatarrives at the testee's pupil may be activated, as described above inconnection with the FIG. 1-9 embodiment.

The embodiments described above in connection with FIG. 10-11 utilizestwo different word types to evaluate whether a testee is beingdeceptive. More specifically, these examples utilize (1) a first-typeword that is expected to evoke significant pupil dilation in a testeewho is being deceptive and not to evoke significant pupil dilation in atestee who is not being deceptive, and (2) second-type words that arenot expected to evoke significant pupil dilation in the testee. (Theinitial word is not relied on to evaluate whether a testee is beingdeceptive.) Optionally, an additional word type (referred to herein asan “third-type word”) may be added to evaluate whether a testee is beingdeceptive. The third-type word 158 is expected to evoke significantpupil dilation in a testee who is not being deceptive, and it operatesin the same way as the third-type sentence 58 described above inconnection with the FIG. 1-9 embodiments.

The embodiments described above in connection with FIGS. 10-11 includeat least one first-type word and a plurality of second-type words (whichare used as a baseline against which to compare the testee's response tothe first-type word). In alternative embodiments, only first-type wordsare used, and these embodiments are analogous to the embodimentsdescribed above in connection with FIG. 8-9 that relied on onlyfirst-type sentences. More specifically, when the number of first-typewords is sufficiently large, it is reasonable to assume that the testeewill not be deceptive with regard to all of the words. And for thosewords, significant pupil dilation is not expected to be evoked in thetestee. In this situation, the testee's non-deceitful responses serve asthe baseline against which the testee's response to the other words arecompared. One suitable approach for selecting the words that will beused as a baseline for comparison is to evaluate the pupil-dilationresponse to each of the words, and select the two words that give riseto the smallest pupil-dilation response as a baseline against which theremaining pupil-dilation responses will be compared. For the remainingwords, evocation of significant pupil dilation is expected if the testeeis being deceptive and not expected if the testee is not beingdeceptive.

The FIG. 1 hardware block diagram and the' description of that figureabove applies with equal force to this embodiment.

The processor/controller 20 controls the audio circuit 30 so that thecircuit outputs an audio signal corresponding to (a) an introductoryphrase or sentence and (b) a set of words. The set of words is outputafter the introductory phrase or sentence, with gaps of at least 2 sinterposed between words within the set. The set of words includes aninitial word and at least three first-type words, and each of thefirst-type words is expected to evoke significant pupil dilation in atestee who is being deceptive and not to evoke significant pupildilation in a testee who is not being deceptive. The initial word ispresented to the testee prior to the presenting of the first-type words,the entire set of words is presented to the testee in less than 2minutes, and the set of words contains less than 20 words. All thefirst-type words are in the same language, and the first-type words allhave volumes within 10 dB of each other.

The processor/controller 20 monitors changes in the testee's pupil sizeduring the presenting of the first-type words and during any responsesto the first-type words made by the testee. The processor/controller 20compares changes in the testee's pupil size in response to each of thefirst-type words to ascertain whether a pupil-dilation response to eachrespective one of the first-type words is at least 10% larger than apupil-dilation response to at least two of the other first-type words,and outputs an indication of deceptiveness or non-deceptiveness for atleast one of the first-type words based on a result of the ascertaining.This may be implemented, for example, by (a) outputting an indication ofdeceptiveness for a respective one of the first-type words when thepupil-dilation response to any given one of the respective first-typewords is at least 10% larger than a pupil-dilation response to at leasttwo of the other first-type words, and/or (b) outputting an indicationof non-deceptiveness when no pupil-dilation response to any given one ofthe first-type words is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type words.

Optionally, these embodiments may also utilize a third-type word toimprove the confidence of the evaluations made by the system. Thethird-type word is expected to evoke significant pupil dilation in atestee who is not being deceptive. In these embodiments, in addition tocomparing the responses to the first-type words (as described above) theprocessor/controller 20 compares changes in the testee's pupil size inresponse to the third-type word with changes in the testee's pupil sizein response to each of the first-type words. The processor/controller 20outputs an indication of deceptiveness for a respective one of thefirst-type words when the pupil-dilation response to the respectivefirst-type word is at least 10% larger than the pupil-dilation responseto at least two of the other first-type words and is also larger thanthe pupil-dilation response to the third-type word. Theprocessor/controller 20 outputs an indication of non-deceptiveness (i)when the pupil-dilation response to each of the first-type words issmaller than the pupil-dilation response to the third-type word or (ii)when the pupil-dilation response to none of the first-type words is atleast 10% larger than the pupil-dilation response to at least two otherfirst-type words.

In today's difficult times, terrorism, crime and deception areunfortunately a daily concern of citizens of most countries around theglobe. It has many faces: cybercrime, suicide bombers, airplanehijacking, murder, theft, fraud, embezzlement, industrial espionage,etc. The embodiments described herein can provide important tools forfighting all of these concerns. Such technologies are advantageouslyapplicable to a dual market: the security/government market (HLS, TSA,military, law enforcement, security agencies, government) and theprivate sector (investigators, lawyers, technology & business companies,health care, insurance, HR, banks, trade floors, and more).

The techniques described herein are also useful as a tool forinvestigation and for screening. As a screening tool, the technologiesdescribed herein can be used for pre-employment checks for candidatesand periodic credibility checks for employees in both markets(security/government and private). In addition, the techniques describedherein can facilitate high throughput screening, which can be verybeneficial in screening crowds at entrances to establishments, borders,and airports for a variety of purposes (e.g., age verification, counterterrorism, or routine screening at customs checkpoints).

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations, and changes to thedescribed embodiments are possible without departing from the sphere andscope of the present invention, as defined in the appended claims.Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

What is claimed is:
 1. An apparatus for evaluating whether a testee isbeing deceptive, the apparatus comprising: an image sensor configured tocapture a plurality of sequential images of the testee's pupil; aprocessor configured to determine a size of the testee's pupil in theplurality of sequential images; a circuit that generates an audiooutput; and a controller programmed to control the circuit so that thecircuit outputs an audio signal corresponding to a set of sentences,wherein the set of sentences includes an initial sentence and at leastthree first-type sentences, wherein each of the first-type sentences isexpected to evoke significant pupil dilation in a testee who is beingdeceptive and not to evoke significant pupil dilation in a testee who isnot being deceptive, and wherein the initial sentence is output prior tothe outputting of the first-type sentences, wherein the controller isfurther programmed to monitor changes in the determined size of thetestee's pupil during the outputting of the first-type sentences andduring any responses to the first-type sentences made by the testee,wherein the controller is further programmed to compare changes in thedetermined size of the testee's pupil in response to each of thefirst-type sentences to ascertain whether a pupil-dilation response toeach respective one of the first-type sentences is at least 10% largerthan a pupil-dilation response to at least two of the other first-typesentences, and wherein the controller is further programmed to output anindication of deceptiveness or non-deceptiveness for at least one of thefirst-type sentences based on a result of the ascertaining, wherein thefirst-type sentences are all in the same language, wherein the averagevolume of each of the portions of the audio signal that corresponds toeach of the first-type sentences are all within 10 dB of each other,wherein each of the first-type sentences has a duration of less than 5s, and wherein gaps of at least 3 s are interposed between adjacentsentences within the set of sentences.
 2. The apparatus of claim 1,wherein the controller is further programmed to (a) output an indicationof deceptiveness for a respective one of the first-type sentences whenthe controller ascertains that the pupil-dilation response to therespective first-type sentence is at least 10% larger than apupil-dilation response to at least two of the other first-typesentences, and (b) output an indication of non-deceptiveness when thecontroller ascertains that no pupil-dilation response to any given oneof the first-type sentences is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type sentences.
 3. Theapparatus of claim 1, wherein portions of the audio signal correspondingto the first-type sentences are output using the same voice, wherein theentire set of sentences is output within 2 minutes, and wherein the setof sentences that is output contains between 4 and 10 sentences.
 4. Theapparatus of claim 1, wherein the controller is further programmed toascertain whether a pupil-dilation response to any given one of thefirst-type sentences is at least 20% larger than a pupil-dilationresponse to at least two of the other first-type sentences.
 5. Theapparatus of claim 1, further comprising an audio amplifier and aspeaker, wherein the audio amplifier receives the audio output from thecircuit, and wherein an output of the audio amplifier drives thespeaker.
 6. The apparatus of claim 1, further comprising a light sourceconfigured to control a level of illumination that arrives at thetestee's pupil in response to instructions received from the controller,wherein the controller is further programmed to send the instructions tothe light source.
 7. The apparatus of claim 1, wherein a singleintegrated circuit serves as both the processor and the controller. 8.The apparatus of claim 1, wherein the set of sentences further includesa third-type sentence that is expected to evoke significant pupildilation in a testee who is not being deceptive, and wherein thecontroller is further programmed to (a) compare changes in the testee'spupil size in response to the third-type sentence with changes in thetestee's pupil size in response to each of the first-type sentences, (b)output an indication of deceptiveness for a respective one of thefirst-type sentences when the controller ascertains that thepupil-dilation response to the respective first-type sentence is atleast 10% larger than the pupil-dilation response to at least two of theother first-type sentences and is also larger than the pupil-dilationresponse to the third-type sentence, and (c) output an indication ofnon-deceptiveness when the controller ascertains that the pupil-dilationresponse to each of the first-type sentences is smaller than thepupil-dilation response to the third-type sentence or when thecontroller ascertains that the pupil-dilation response to none of thefirst-type sentences is at least 10% larger than the pupil-dilationresponse to at least two other first-type sentences.
 9. The apparatus ofclaim 1, wherein the grammatical structure, duration, level ofcomplexity, and language style of all the first-type sentences aresimilar.
 10. The apparatus of claim 1, wherein each of the first-typesentences includes a respective keyword, and wherein the position of therespective keyword within each of the first-type sentences is similar,wherein any two given keywords are deemed to have a similar positionwithin a respective sentence when the two given keywords are either (a)both positioned in the initial one-third of the respective sentence, (b)both positioned in the middle one-third of the respective sentence, or(c) both positioned in the last one-third of the respective sentence.11. A method of evaluating whether a testee is being deceptive, themethod comprising: presenting a set of sentences to the testee, whereinthe set of sentences includes an initial sentence and at least threefirst-type sentences, wherein each of the first-type sentences isexpected to evoke significant pupil dilation in a testee who is beingdeceptive and not to evoke significant pupil dilation in a testee who isnot being deceptive, and wherein the initial sentence is presented tothe testee prior to the presenting of the first-type sentences;monitoring changes in the testee's pupil size during the presenting ofthe first-type sentences and during any responses to the first-typesentences made by the testee; comparing changes in the testee's pupilsize in response to each of the first-type sentences to ascertainwhether a pupil-dilation response to each respective one of thefirst-type sentences is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type sentences; andoutputting an indication of deceptiveness or non-deceptiveness for atleast one of the first-type sentences based on a result of theascertaining, wherein the first-type sentences are all in the samelanguage, wherein the average volume of each of the first-type sentencesis within 10 dB of each other, wherein each of the first-type sentenceshas a duration of less than 5 s, and wherein gaps of at least 3 s areinterposed between adjacent sentences within the set of sentences. 12.The method of claim 11, wherein the outputting comprises (a) outputtingan indication of deceptiveness for a respective one of the first-typesentences when the comparing reveals that the pupil-dilation response tothe respective first-type sentence is at least 10% larger than apupil-dilation response to at least two of the other first-typesentences, and (b) outputting an indication of non-deceptiveness whenthe comparing reveals that no pupil-dilation response to any given oneof the first-type sentences is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type sentences.
 13. Themethod of claim 11, wherein the first-type sentences are all in the samevoice, wherein the entire set of sentences is presented to the testeewithin 2 minutes, and wherein the set of sentences that is presented tothe testee contains between 4 and 10 sentences.
 14. The method of claim11, further comprising controlling a level of illumination that arrivesat the testee's pupil.
 15. The method of claim 11, wherein the set ofsentences further includes a third-type sentence that is expected toevoke significant pupil dilation in a testee who is not being deceptive,and wherein the method further comprises (a) comparing changes in thetestee's pupil size in response to the third-type sentence with changesin the testee's pupil size in response to each of the first-typesentences, (b) outputting an indication of deceptiveness for arespective one of the first-type sentences when a pupil-dilationresponse to the respective first-type sentences is at least 10% largerthan the pupil-dilation response to at least two of the other first-type sentences and is also larger than the pupil-dilation response tothe third-type sentence, and (c) outputting an indication ofnon-deceptiveness when the pupil-dilation response to each of thefirst-type sentences is smaller than the pupil-dilation response to thethird-type sentence or when the pupil-dilation response to none of thefirst-type sentences is at least 10% larger than the pupil-dilationresponse to at least two other first-type sentences.
 16. The method ofclaim 11, wherein the grammatical structure, duration, level ofcomplexity, and language style of all the first-type sentences aresimilar.
 17. The method of claim 11, wherein each of the first-typesentences includes a respective keyword, and wherein the position of therespective keyword within each of the first-type sentences is similar,wherein any two given keywords are deemed to have a similar positionwithin a respective sentence when the two given keywords are either (a)both positioned in the initial one-third of the respective sentence, (b)both positioned in the middle one-third of the respective sentence, or(c) both positioned in the last one-third of the respective sentence.18. An apparatus for evaluating whether a testee is being deceptive, theapparatus comprising: an image sensor configured to capture a pluralityof sequential images of the testee's pupil; a processor configured todetermine a size of the testee's pupil in the plurality of sequentialimages; a circuit that generates an audio output; and a controllerprogrammed to control the circuit so that the circuit outputs an audiosignal corresponding to (a) an introductory phrase or sentence and (b) aset of words, wherein the set of words is output after the introductoryphrase or sentence, with gaps of at least 2 s interposed between wordswithin the set, wherein the set of words includes an initial word and atleast three first-type words, wherein each of the first-type words isexpected to evoke significant pupil dilation in a testee who is beingdeceptive and not to evoke significant pupil dilation in a testee who isnot being deceptive, wherein the initial word is presented to the testeeprior to the presenting of the first-type words, wherein the entire setof words is presented to the testee in less than 2 minutes, and whereinthe set of words contains less than 20 words; wherein the controller isfurther programmed to monitor changes in the testee's pupil size duringthe presenting of the first-type words and during any responses to thefirst-type words made by the testee; wherein the controller is furtherprogrammed to compare changes in the testee's pupil size in response toeach of the first-type words to ascertain whether a pupil-dilationresponse to each respective one of the first-type words is at least 10%larger than a pupil-dilation response to at least two of the otherfirst-type words; and wherein the controller is further programmed tooutput an indication of deceptiveness or non-deceptiveness for at leastone of the first-type words based on a result of the ascertaining,wherein the first-type words are all in the same language, and whereinthe first-type words all have volumes within 10 dB of each other. 19.The apparatus of claim 18, wherein the controller is further programmedto (a) output an indication of deceptiveness for a respective one of thefirst-type words when the controller ascertains that the pupil-dilationresponse to the respective first-type word is at least 10% larger than apupil-dilation response to at least two of the other first-type words,and (b) output an indication of non-deceptiveness when the controllerascertains that no pupil-dilation response to any given one of thefirst-type words is at least 10% larger than a pupil-dilation responseto at least two of the other first-type words.
 20. The apparatus ofclaim 18, wherein the controller is further programmed to control alevel of illumination that arrives at the testee's pupil.
 21. Theapparatus of claim 18, wherein the set of words further includes athird-type word that is expected to evoke significant pupil dilation ina testee who is not being deceptive, and wherein the controller isfurther programmed to (a) compare changes in the testee's pupil size inresponse to the third-type word with changes in the testee's pupil sizein response to each of the first-type words, (b) output an indication ofdeceptiveness for a respective one of the first-type words when thecontroller ascertains that the pupil-dilation response to the respectivefirst-type word is at least 10% larger than the pupil-dilation responseto at least two of the other first-type words and is also larger thanthe pupil-dilation response to the third-type word, and (c) output anindication of non-deceptiveness when the controller ascertains that thepupil-dilation response to each of the first-type words is smaller thanthe pupil-dilation response to the third-type word or when thecontroller ascertains that the pupil-dilation response to none of thefirst-type words is at least 10% larger than the pupil-dilation responseto at least two other first-type words.
 22. The apparatus of claim 18,wherein all the first-type words are presented in the same voice. 23.The apparatus of claim 22, wherein all the first-type words have asimilar level of complexity and a similar language style.
 24. A methodof evaluating whether a testee is being deceptive, the methodcomprising: presenting an introductory phrase or sentence to the testee;presenting a set of words to the testee after the introductory phrase orsentence has been presented to the testee, with gaps of at least 2 sinterposed between words within the set, wherein the set of wordsincludes an initial word and at least three first-type words, whereineach of the first-type words is expected to evoke significant pupildilation in a testee who is being deceptive and not to evoke significantpupil dilation in a testee who is not being deceptive, wherein theinitial word is presented to the testee prior to the presenting of thefirst-type words, wherein the entire set of words is presented to thetestee in less than 2 minutes, and wherein the set of words containsless than 20 words; monitoring changes in the testee's pupil size duringthe presenting of the first-type words and during any responses to thefirst-type words made by the testee; comparing changes in the testee'spupil size in response to each of the first-type words to ascertainwhether a pupil-dilation response to each respective one of thefirst-type words is at least 10% larger than a pupil-dilation responseto at least two of the other first-type words; and outputting anindication of deceptiveness or non-deceptiveness for at least one of thefirst-type words based on a result of the ascertaining, wherein thefirst-type words are all in the same language, and wherein thefirst-type words all have volumes within 10 dB of each other.
 25. Themethod of claim 24, wherein the outputting comprises (a) outputting anindication of deceptiveness for a respective one of the first-type wordswhen the comparing reveals that the pupil-dilation response to therespective first-type word is at least 10% larger than a pupil-dilationresponse to at least two of the other first-type words, and (b)outputting an indication of non-deceptiveness when the comparing revealsthat no pupil-dilation response to any given one of the first-type wordsis at least 10% larger than a pupil-dilation response to at least two ofthe other first-type words.
 26. The method of claim 24, furthercomprising controlling a level of illumination that arrives at thetestee's pupil.
 27. The method of claim 24, wherein the set of wordsfurther includes a third-type word that is expected to evoke significantpupil dilation in a testee who is not being deceptive, and wherein themethod further comprises (a) comparing changes in the testee's pupilsize in response to the third-type word with changes in the testee'spupil size in response to each of the first-type words, (b) outputtingan indication of deceptiveness for a respective one of the first-typewords when the pupil-dilation response to the respective first-type wordis at least 10% larger than the pupil-dilation response to at least twoof the other first-type words and is also larger than the pupil-dilationresponse to the third-type word, and (c) outputting an indication ofnon-deceptiveness when the pupil-dilation response to each of thefirst-type words is smaller than the pupil-dilation response to thethird-type word or when the pupil-dilation response to none of thefirst-type words is at least 10% larger than the pupil-dilation responseto at least two other first-type words.
 28. The method of claim 24,wherein all the first-type words are presented in the same voice. 29.The method of claim 28, wherein all the first-type words have a similarlevel of complexity and a similar language style.